The Bioware blog recently posted about this information, which I'll summarize here.
Mechanics
Earning reputation in Mass Effect 3 is a bit different from the first two games. Rather than earning only Paragon and Renegade points, you can also earn Neutral reputation, so there are 3 types of rep in ME3.
This means you can now mix being Paragon/Renegade without worrying about getting locked out of the more difficult Charm/Intimidate options. When you earn Paragon/Renegade rep, it'll show up as Blue/Red, whereas if you earn Neutral rep, it'll increase your reputation bar's size as a whole while retaining the same blue/red ratio.
Click through for the larger version.
Your total reputation (blue/red/neutral) will determine whether or not you'll be able to pass a Charm/Intimidate block. The lines on the bar are "checkpoints" which serve as gates for more difficult dialogue options. I marked them with the thin lines of red, in case it was difficult to see (this is not my Shep, this is the photo from the blog post).
As per usual, you get rep from completing missions and making dialogue choices. For missions with no Paragon/Renegade choice but still have a large impact, you will get Neutral rep.
Story Impact
In contrast to older Bioware games, you can never actually be the villain in ME3, though this should be rather clear from how they handled the first 2 games. No matter what, you will be fighting to save the galaxy. The manner in which you do it will be what differentiates a Paragon from a Renegade. Also, bullying people into giving you more money or discounts won't be the crux of what makes a Renegade decision in this game. Who needs credits if there's nowhere to spend them because civilized life has been destroyed?
Reputation gain will be based on when you have to make a decision in the game. Here are a few examples of what kind of rep you would get, taken from the blog:
- Confronted on the Citadel by a desperate refugee with a gun, you give her some credits and help her find a place to sleep. (Paragon)
- As a human colony falls to Reaper forces, you order down an orbital strike, brutally killing thousands of colonists to prevent the Reapers from turning them into husks. (Renegade)
- You land at a turian fuel depot taken by Reaper forces and clear it out, enabling allied forces to keep fighting. (General Reputation)
TL;DR
BioWare has finally made a single-player game that lets you make morally grey choices without nerfing yourself, gameplay-wise. Rejoice!
Any projectiles which benefit from the piercing (in this case, penetrate a .5 meter thick object) will deal reduced damage (60%). Projectiles which don't need to penetrate cover or an obstacle to hit their target do normal damage. This includes the visual armor that Husks / Cannibals can get, and the shields of Cerberus Guardians.
Additionally, depending on the type of enemy and the difficulty, some enemies have "Armor" (not to be confused with the yellow Armor bar some enemies have on top of / instead of health). This armor reduces damage by a flat amount, and it is this Armor that the piercing mod works against. So you do get some benefit when attacking all colors of health bar.
Best Answer
As far as I know, each class has a predefined build, but the auto leveler also tries to allocate any skill points available. In ME1, this wasn't really a problem, as you only needed one skill point to increase any skill at any level. With ME2 and ME3, each time you advance a skill it requires one more skill point. You'd be prudent to save up some skill points for one of your key skills, but the auto leveler doesn't do this. Early in the game, this may be fine, as it unlocks all your skills, but later, you and your squad become jacks of all trades, but masters of none. It's a lot better to have one skill that does a lot of damage (or provides a lot of defence) and recharges fast, than having a lot of skills that do an okay amount of damage, but don't recharge any faster, and in some cases, recharge a lot slower.